The section describes Poisson Solver routines for the Cartesian case,
their syntax, parameters, and return values. All flavors of the same routine are described
together: single- and double-precision and 2D and 3D.
Some of the routine parameters are used only in the 3D Fast Helmholtz
Poisson Solver routines call
Intel® oneAPI Math Kernel
FFT routines (described inFFT Functions), which enhance
performance of the Poisson Solver routines.